U.S. Pat. No. 4,409,214 disclosed 7-Acylamino-3-vinylcephalosporanic acid derivatives and pharmaceutically acceptable salts thereof. These compounds are antibacterial agents. Among them Cefixime, chemically 7-[2-(2-amino-4-thiazolyl)-2-(carboxymethoxyimino)acetamido]-3-vinyl-3-cephem-4-carboxylic acid is an orally active cephalosporin antibiotic and is more potent against gram-negative bacteria. Cefixime is represented by the following structure:

Processes for the preparations of Cefixime and related compounds were disclosed in U.S. Pat. No. 4,409,214, J. Antibiotics (1985), 38, 1738 and WO 95/33753, U.K. Patent Application No. 2 330 140, U.K. Patent Application No. 2 330 141, U.S. Pat. No. 6,313,289, WO 98/06723 and U.S. Pat. No. 6,800,755 B2.
U.K. Patent Application No. 2 330 141 described the process for preparing cefixime by hydrolyzing in a halogenated aliphatic hydrocarbon (e.g., methylenedichloride) ester compound of formula-A:
wherein R represents (C1-C4) alkyl group;with potassium carbonate in the presence of phase transfer catalyst at ambient temperature for 30-90 minutes.
U.K. Patent Application No. 2 330 140 described a process for preparing cefixime by treating the compound of formula A with an inorganic base in dim ethyl formamide and water for 1 hour 30 minutes to 2 hours and isolating cefixime.
U.S. Pat. No. 6,800,755 B2 described a process for preparing cefixime by dissolving alkyl ester of formula A in water and water immiscible solvent such as ethyl acetate using sodium bicarbonate, hydrolyzing with sodium hydroxide at 0-25° C. and isolating cefixime by acidifying the reaction mass.
The processes described in U.K. Patent Application No. 2 330 141, U.K. Patent Application No. 2 330 140 and U.S. Pat. No. 6,800,755 B2 suffer from any of the following problems: a) color and quality are poor, b) contamination of cefixime with high boiling point solvent such as dimethyl formamide. The removal of the residual solvents is difficult owing to sensitivity of cefixime to high temperature.
J. Antibiotics (1985), 38, 1738 described processes for preparing cefixime involving protection and deprotection steps. The processes described required purification of cefixime by column chromatography. Methods involving column chromatographic purifications cannot be used for large-scale operations, thereby making the process commercially not viable.
Process for preparing cefixime described in U.S. Pat. No. 4,409,214 and WO 95/33753 are lengthy involving many protecting and deprotecting steps and so not commercially viable.
U.S. Pat. No. 6,313,289 B1 described the purification of cefixime by forming a crystalline amine salt of crude cefixime, converting the salt into sulfuric acid addition salt of cefixime and recovering pure cefixime from sulfuric acid addition salt of cefixime.
WO 98/06723 is related to cefixime dicyclohexyl amine salt and purification of cefixime via dicyclohexyl amine salt.
The purification of cefixime by the processes described in U.S. Pat. No. 6,313,289 B1 and WO 98/06723 are lengthy and complicated involving many crystallizations, neutralizations and salt formations.
The present invention is an improved, commercially viable process solving the aforesaid problems associated with processes described in the prior art.